Overrunning clutches of the type known as concentric control clutches are used when it is desired to maintain a pair of clutch races in coaxial relation without the use of separate bearings. Such clutches have cages that include support portions designed to maintain the annular spacing between the races, thereby maintaining the races substantially coaxial. Although, such cage assemblies may be formed entirely of metal, it is often desirable that the support portions, generally referred to as journal blocks, be formed of plastic. Certain surfaces of the journal blocks will ride upon and slide over a surface of one of the clutch races when the clutch is in the overrunning mode, and plastic has superior desirable frictional characteristics, in addition to its light weight, low cost and moldability. It is also generally desirable that the journal blocks be manufactured as circumferentially separate pieces, rather than as an integral part of a unitary plastic cage assembly. This is so because plastic generally has a far higher coefficient of expansion than metal. A unitary plastic cage that is confined within the annular space between a pair of metal clutch races, may present binding or buckling problems as it more rapidly expands or contracts within that annular space with changing temperature. Separate journal blocks, on the other hand, can move circumferentially toward and away from each other essentially independently, and do not present the problem found with a unitary cage. However, it is inevitably more difficult and expensive to manufacture and assemble a cage assembly having a plurality of separate pieces. Another potential problem with a cage formed as a plastic unitary structure is that it does not provide armored retention pockets for the clutch wedging elements, which are generally metal cylindrical rollers.
Several designs for concentric control cages having separate plastic journal blocks may be found in U.S. patents. For example, the U.S. Pat. No. 4,187,937 to Kitchin, assigned to the assignee of the present invention, shows a roller clutch having a metal end ring with a plurality of circumferentially spaced retention tabs formed integrally therewith. A plurality of separately molded and separately handled plastic journal blocks are then snap fitted to each of the metal end ring tabs to complete the cage assembly. Although this provides a complete and workable structure, it does have the separate piece assembly drawback referred to above. However, the circumferentially separate journal blocks, which can float toward or away from one another independently, do provide better operation under conditions of extreme temperature changes than would a unitary plastic cage. Therefore, the extra assembly cost has been tolerated in the past because of the operational of the separate journal blocks.